Installation with CASTEP

You will need the following program components:

QUIP with GAP
- MPI-only library for linking to Castep
- OpenMP gap_fit program
CASTEP: Academic release v22 and above
Python installation of hybrid-md - bundled with GAP

The two builds of QUIP are needed due to the different parallelism supported by the fitting and evaluation.

Linux - general setup

These are general instructions for a Linux machine, assuming the libraries needed for the respective packages are installed. See documentation of QUIP & CASTEP for these.

QUIP+GAP installations

Clone the code, make sure to include the subpackages as well using the –recursive flag.

# clone the QUIP repository
git clone --recursive https://github.com/libAtoms/QUIP.git
cd QUIP

Build the OpenMP version for fitting

# arch: any compiler + OpenMP
export QUIP_ARCH=linux_x86_64_gfortran_openmp

# configure: build - Make sure to say yes to GAP
make config

# build: the gap_fit program
make gap_programs

# copy the executable to your desired installation directory
cp ./build/$QUIP_ARCH/gap_fit ...your bin dir...

Build an MPI library version for linking to Castep. Make sure to use the same compiler as for the Castep installation later on.

# still in the QUIP directory created above

# remember this directory for configuring CASTEP
export QUIP_ROOT=$(pwd)

# arch: any compiler + MPI
export QUIP_ARCH=linux_x86_64_gfortran_openmpi

# configure build - Make sure to say yes to GAP
make config

# build: only the library
make libquip.a

Castep

See the installation notes and documentation in your CASTEP source distribution, the relevant part for this program is the inclusion of QUIP, which you can do by specifying QUIP=system in the main Makefile plus providing the QUIP_ROOT (root directory of QUIP repo) and QUIP_ARCH (the MPI one). These can be directly placed into the Makefile of CASTEP as well to be exported for easier resume of build or rebuild later.

# make sure these are specified
COMMS_ARCH := mpi
QUIP := system

# example of explicitly setting the location of QUIP
export QUIP_ROOT=...directory from above...
export QUIP_ARCH=linux_x86_64_gfortran_openmpi

Having set these, just build and install CASTEP.

`hybrid-md` Python package

Simply install in the package from source, found in the GAP/hybrid_md_package/ directory of this repo.

This is located at QUIP/src/GAP/hybrid_md_package/ if you are looking at the QUIP source downloaded above.

python -m pip install .

Archer2 cluster

These are specific and tested instructions the UK’s Archer2 https://www.archer2.ac.uk computer cluster.

An important gotcha on Archer2 is that the built-in maths libraries of the compiler are linking MPI by default, which breaks the setup for the gap_fit program, so we need to build that explicitly without MPI, see below.

Edit the CASTEP Makefile to include the following

COMMS_ARCH := mpi
FFT := fftw3
BUILD := fast
MATHLIBS := mkl # optional

Full installation:

# create bin directory for executables
mkdir bin

# Clone QUIP
git clone --recursive https://github.com/libAtoms/QUIP.git --depth 1 --single-branch

# load the correct modules
module load cray-python
module switch PrgEnv-cray PrgEnv-gnu/8.1.0
module load cpe/22.04
module load cray-fftw
module load mkl/2023.0.0  # if using MKL for Castep

# step 1: Python interpreter & installation of hybrid-md
python -m virtualenv venv
source venv/bin/activate

python -m pip install ./QUIP/src/GAP/hybrid_md_package/

# step 2: QUIP with MPI
cd QUIP
export QUIP_ROOT=$(pwd)
export QUIP_ARCH=archer2_mpich
make config   # configure: build - Make sure to say yes to GAP
make libquip.a
cd ../ # back to the starting dir

# step 3. CASTEP with linking QUIP
cd CASTEP/
make -j8
cp obj/linux_x86_64_gfortran10-XT--mpi/castep.mpi ../bin/
cd ../ # back to the starting dir

# step 4. Install gap_fit

# IMPORTANT!! unload comms modules -> no MPI
module load craype-network-none
module remove cray-mpich

cd QUIP
export QUIP_ARCH=archer2_openmp
make gap_programs
cp build/archer2_openmp/gap_fit ../bin/
cd ../ # back to the starting dir